I've found your typo.
href="<{$xoops_url}>/user.php"><{$xoops_uname}></a> !<{else}>
<form onkeyup="highlight(event)" onclick="highlight(event)" style="margin-top: 2px; margin-bottom: 0px" action="<{$xoops_url}>/user.php" method="post">
<input name="uname" onblur="if(this.value=='') this.value='Username';" onfocus="if(this.value=='Username') this.value='';" type="text" value="Username" size="10" />
<input onblur="if(this.value=='') this.value='Password';" onfocus="if(this.value=='Password') this.value='';" value="Password" name="pass" type="password" size="10" />
<input type="hidden" name="op" value="login" />
<input type="hidden" name="xoops_redirect" value="<{$xoops_requesturi}>" />
<input name="submit" type="submit" value="Login" />
<input type="checkbox" name="rememberme" value="On" class ="formButton" />remember me <br/>
</form>
<{/if}></td>
<td align="left" class="headercenter"> <{if $xoops_isuser}> <{else}>
<form style="margin-top: 2px; margin-bottom: 0px" action="<{$xoops_url}>/register.php" method="post">
<input name="submit" type="submit" value=" Join " />
</form>
<{/if}> </td>